Summary of Treasury Stock Activity (Detail) $ in Thousands	6 Months Ended
	Jun. 30, 2016 USD ($) shares
Schedule of Treasury Stock [Line Items]
Beginning Balance, Shares | shares	4,183,504
Restricted stock withholdings | shares	205,860	[1]
Restricted stock forfeitures | shares	31,243
Ending Balance, Shares | shares	4,420,607
Beginning Balance, Cost | $	$ 66,577
Restricted stock withholdings | $	6,802	[1]
Restricted stock forfeitures | $	0
Ending Balance, Cost | $	$ 73,379

[1] The Company withheld restricted shares as a result of the election by certain employees to satisfy their tax liabilities upon vesting in restricted stock and restricted stock units. The Company determined the number of shares to be withheld based upon market values ranging from $29.17 to $35.83 per share.